Bell cap arrangement



Aug. 10, 1954 GREEN ET AL 2,686,046

BELL CAP ARRANGEMENT Filed March 14, 1952 FOLDED Am: uPPED P nul Q.dream arm/eaters Hank J: e/zmiel @ESL 7 Clttorae;

Patented Aug. 10, 1954 BELL CAP ARRANGEMENT Paul R. Green, Cranford, andFrank J. Chmiel,

Union, N. J., assignors to Standard Oil Development Company, acorporation of Delaware Application March 14, 1952, Serial No. 276,714

4 Claims.

This invention concerns a novel and improved form of bell cap of thenature used in distillation towers. The invention particularly concernsuse of a cup-shaped deflector insert beneath a bell cap member toprovide a streamlined vapor passage over the chimney with which the bellcap is employed. The deflector insert is adapted for utilization withconventional types of hell cap constructions, permitting conversion toan improved streamlined flow type of hell cap arrangement.

For many years a desirable form of contacting apparatus has been a towerarrangement in which perforated plates provided with bubble cap membersare employed. Such towers are particularly employed in distillationoperations involving the contacting of vapors and liquids. The bell typebubble caps are employed to permit the upflow of vapors through theperforated plates referred to, while preventing the downflow of liquidthrough the bubble cap members. The bubble caps, therefore, provide thefunction of permitting vapor to pass from a lower plate member throughan upper member and through the liquid maintained on the upper platephase to secure successive vapor liquid contacting.

A wide variety of bubble cap arrangements may be employed to secure thegeneral objectives indicated. In general, however, a typical bubble capassembly comprises a chimney element extending above each of theperforations of the plates employed. An inverted cup-shaped bubble capis positioned over this chimney element so as to provide a dependentskirt portion extending below the upper termination of the chimney.Suitable holding arrangements are employed to fix the bubble cap at aspecified distance above the chimney in this manner. The skirt of thebubble cap member is slotted or notched along its lower periphery topermit vapors rising upwardly through the chimney to pass outwardlythrough the slots into the liquid maintained on the plate.

The principal problem in connection with the provision of improved formsof bubble cap elements is concerned with practical limitations of use.For example, it is important that the construction employed be such asto permit convenient removal or servicing of the bubble cap arrangement.A practical difficulty which has been observed is the tendency forcarbonaceous or coke-like deposits to form on the threaded holdingelements generally employed, so as to complicate or prevent removal ofthe bubble cap. One of the objects of this invention is to provide abubble cap arrangement which by its nature will avoid this difiicultycaused by deposition of carbonaceous deposits on the holding meansemployed.

It is now generally appreciated that improved tower performance may beobtained by streamlining the flow of vapor upwardly through a chimney inthe bubble cap arrangement. A desirable streamlined passage forupflowing vapors may be provided by forming the lower inside surface ofthe bell cap member in a cup-shaped configuration. This will provide adeflecting surface for upflowing vapors, tending to direct the vaporsoutwardly over the upper edge of the chimney with a minimum ofturbulence. Provision for streamlining vapor flow through a bubble cap,therefore, has the efiect of decreasing the vapor pressure drop acrossthe bubble cap arrangement. It is a further object of this invention toprovide an improved form of bubble cap arrangement which simply andeifectively provides the desired streamlined passage through the bubblecap.

In its simplest form the present invention comprises a deflector inserthaving a general conical shape. This deflector is to be positionedcentrally beneath a bell cap so as to provide deflecting surfaces forthe vapor which are inclined upwardly and outwardly toward the chimneyelement. The deflector can well be designed to include standoff lugsadapted to rest directly on the chimney element. By passing a hold-downbolt through the bell cap and through the deflector to be anchored tothe plate on which the bell cap is positioned, the entire arrangementwill be held in a fixed position. The invention is of such anature as toparticularly permit modification of existing bubble cap arrangements toincorporate the streamlined vapor flow employed.

The accompanying drawings fully illustrate the present invention:

Figure 1 of the drawings illustrates the integral bubble cap arrangementof this invention in a cross-sectional perspective view;

Figure 2 is a perspective view of one form of deflector element whichmay be employed in the apparatus of Figure 1, and finally Figure 3 is aperspective view of an alternative form of deflector insert embodyingthis invention.

Referring now to Figure 1, the nature and principle of this inventionmay be understood. A fragmental view of a perforated plate equipped withbell type bubble caps is illustrated. The portion of the plate shown isdesignated by numeral l. A chimney element which can simply comprise acylindrical sleeve 2 is fixed to plate I over a perforation cut in theplate. The chimney element may, if desired, be cast or formed as anintegral portion of the plate in the manner particularly illustrated. Abell cap member 3 is fixed above the chimney element and essentiallycomprises an inverted cup-shaped member. The bell cap is constructed tohave a substantially greater diameter than the chimney so that thedependent skirt of the. bell capcan extend below the upper edge of thechimney whilebeing displaced from the chimney. A large number ofperforations 4 are cut in the lower edge of the bell cap. Theseperforations may simply consist of elongated slots, but are preferablytriangular in configuration, as shown. The slots are=cut soas to extendupwardly from the edge ofithe bell cap to an elevation substantiallythatof the uppermost part of the chimney element 2.

In accordance with this invention a deflector element 5 is centrallypositioned beneath the lower side of the bubble cap 3. As will be seen,deflector 5 is maintained in a clamped relation with the bell cap 3. Anumber of vertical bracket lug members 6 may be fixed to the deflector 5adapted to seat on the chimney element 2. For example, three radiallydisposed bracket lug members 6 may be employed. It is the function ofthese members to space the deflector 5 andthe bell cap 3 with relationto the chimney 2. In this connection, the bracket members are preferablyshaped to center the bell cap arrangement as well as to space the bellcap above the chimney. For this purpose each of the bracket members 6will be notched in the manner illustrated so as to maintain a fixedlocked position when the bell cap arrangement is assembled.

A suitable hold-down arrangement is employed to force the bell cap 3downwardly against deflector 5 which in turn is forced against the topof the chimney 2. For example, a hold-down bolt i may be employed. Oneend of bolt 1 may be fixed in or threaded in a bar member 8 ofsufficient length to extend across the perforation of the plate. Theother end of the bolt 1 may be threaded to accommodate a nut 9 which maybe tightened to fix the entire bubble cap arrangement in a clampedposition.

The center opening cut in the deflector 5 to accommodate the hold-downbolt 1 is preferably such as to permit a forced fit of the bolt withinthis opening. It is practical to accomplish this so as to substantiallyprovide a fluid-tight seal at this point. Alternatively, if desired, asimple form of packing member, or grommet may be employed to preventpassage of vapor upwardly along bolt '1 past the deflector.

In its simplest form the deflector 5 may consist of a conical memberproviding an inclined surface extending upwardly from the centralposition or L-h chimney toward the-outer periphery of the bell cap.Somewhat improved streamlined flow will be obtained, however, byparticularly shaping deflector 5 to have the curved cup shapeillustrated. This shape further minimizes turbulence caused bydeflection of vapor from the chimney into the bell cap.

A particular feature of the arrangement described is the fact that thebell cap construction is devoid of any hollow or cup-shaped recesses inwhich liquid can deposit. Thus the upper portion of bell cap 3 may, asillustrated, constitute a horizontal plate surface. While liquidmay-condense on the surface during distillation operations, liquid willfreely flow downwardly over the edges of the bell cap. Consequently, thethreads of bolt 9 can not be plugged by deposition of carbonaceousdeposits caused by hold-up of hydrocarbon liquids on the bell cap. Thisobviously can be furthered, if desired, by somewhat curving the uppersurface of the bell cap to facilitate drainage of liquid from the top ofthe bell cap.

It is apparent that any desired type of standoff arrangement may beemployed to perform the function of the bracket 6. For example, ifdesired, a collar element l0 may be provided on bolt 1 against which thelower portion of deflector 5 may bear. The bracket 6 may in this case besimplified Or dispensed with. Tightening of nut 9 will permit fixedclamping of the element in the general manner described. In this case,if desired, a spider or other centralizing spacer may beemployed withinthe chimney 2.

Again the bracket member 6 may be modified or replaced by simplestandofi rods which are preferably notched to fit over the upper edge ofthe chimney tube. These standoff rods being fixed to the deflector 5will permit clamping of the entire arrangement on tightening of nut 9 inthe same manner as that described.

The deflector element 5 may be formed in any desired manner. Thus, ifdesired, the deflector may be cast or pressed to provide theconfiguration illustrated. Two particular methods of fabrication areillustrated in Figures 2 and 3. In Figure2 illustrating the deflector.5, the deflector is essentially formed from a circular sheet of metal.This sheet is pressed to form the cup shape illustrated, at the sametime causing folding of the metal at three or more radial portions ofthe deflector. This will result in the provision of downwardly dependentrib or bracket elements l2. By cutting a notch 13 near the edge of eachof these bracket elements, the deflector will be complete andreadyforinsertion in a bubble cap arrangement in the manner described.

In Figure 3, the deflector 5 is formed by cold pressing or otherwiseshaping the circular metal blank. employed. The operation is conductedto form this blank into the cup-shaped configura tion illustrated.Bracket members It may then be welded to the lower side of th cup-shapeddeflector to provide the complete deflector element. It is apparent thatthese or other techniques may be employed tosuitably form a defiectorfor use in-this invention.

As brought out, therefore, this invention concerns a novel and desirableform of bubble cap arrangement in which a deflector element ispositioned over a bubble cap chimney beneath a bell cap member.The-deflector element has a generally conical shape to provide anupwardly and outwardly flaring surface for the direction of vaporsupwardly'through the chimney and outwardly toward the periphery of thebell cap. In its preferred form the invention concerns the use of thisdeflector element in combination with a bell cap having a substantiallyplane surface. The combination of the deflector with a bell cap of thisnature permits the desired streamlined direction of vapors referred towithout permitting the possibility for hold-up of liquid above the bellcap. It will be observed in this connection that'the d'eiiector'of thisinvention is ideally qualified for the conversion of standard bubble caparrangements to the streamlined type of arrangement. Thus bell caps ofthe nature referred to are commonly employed at the present time.Inclusion of the deflector element described in conventional bubble caparrangements may therefore simply be made to provide the benefits ofthisinvention.

What is claimed is:

1. In a bubble cap arrangement comprising a perforated plate, a chimneyelement surmounting said plate over each of the perforations, and a bellcap member spaced above the chimney, the improvement which comprises: adeflector element adapted to be placed within the bell cap over the saidchimney, said deflector being characterized by an inclined surfacedirected upwardly toward the periphery of the bell cap, standoflelements fixed to the underside of said deflector adapted to seat onsaid chimney, and means to clamp said bell cap to said deflector andsaid chimney, whereby said deflector spaces and positions said bell capwith respect to the chimney.

2. The apparatus defined by claim 1 in which the said deflector elementhas a generally conical configuration.

3. The apparatus defined by claim 1 in which the said deflector elementis cup-shaped.

4. An article of manufacture comprising a deflector element for use inbubble cap trays comprising a cup-shaped plate member having a centralopening, at least three bracket elements fixed to the lower portion ofthe said cup-shaped member extending radially from the center of themember, said" bracket elements including notched portions adjacent theirends.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,857,816 Lichtenthal-er May 10, 1932 1,918,005 Urquhart July11, 1933 2,084,726 Duey June 22, 1937 2,205,284 Eckart June 18, 19402,320,822 Kerrigan June 1, 1943

